Assessment of natural radioactivity levels and radiation hazard indices for soil samples from Abha, Saudi Arabia

The natural level of radioactivity in the soil is one of the main causes of external gamma exposure. It was considered necessary to measure concentrations of gamma ray activity due to naturally occurring, potentially hazardous radionuclides from, Ra-226, Th-232 and K-40 for soil samples collected from different locations (Abha, Khamis Mushait and Muhail Asir) in Asir region. The samples were analyzed for its naturally occurring radionuclides by gamma-ray spectrometry using NaI (Tl). The results show that the average values of activity for Ra-226, Th-232 and K-40 in range of 38.2 +/- 0.1-44.1 +/- 0.1, 23.49 +/- 0.20-41.9 +/- 0.2 and from 182.5 +/- 1.0 to 251.5 +/- 1.3 Bq Kg(-1) respectively. Also the frequency distribution for all radioactive variables in soil was analyzed. Additionally evaluations have been made of the radiological hazards and it's diagramed by Surfer program in maps. These data will serve as the baseline level of radionuclides that occur naturally in the study area and will be useful for tracking and assessing any pollution inventory in the environment of this region.